Methods of modifying oxide spacers

Abstract

Methods for reducing line roughness of spacers and other features utilizing a non-plasma and non-wet etch fluoride processing technology are provided. Embodiments of the methods can be used for spacer or line reduction and/or smoothing the surfaces along the edges of such features through the reaction and subsequent removal of material.

What is claimed is: 
     
       1. A method of etching a material layer, comprising:
 forming a patterned temporary material having sidewalls and a horizontal surface over an underlying material; 
 forming an oxide material onto the patterned temporary material; 
 removing the oxide material from the horizontal surface of the patterned temporary material to form oxide spacers on the sidewalls of the patterned temporary material; 
 removing the patterned temporary material to form vertical, free-standing and spaced-apart oxide spacers having a length, vertical surfaces with convex and concave portions, and an initial critical dimension that is variable along the length; 
 exposing the vertical, free-standing and spaced-apart oxide spacers to an ammonium fluoride gas to convert the convex portions of the vertical surfaces of the vertical, free-standing and spaced-apart oxide spacers to a heat decomposable compound; 
 removing at least a portion of the heat decomposable compound to obtain a uniform critical dimension along the length of the vertical, free-standing and spaced-apart oxide spacers; and 
 removing the underlying material exposed within openings between the vertical, free-standing and spaced-apart oxide spacers. 
 
     
     
       2. The method of  claim 1 , wherein exposing the vertical, free-standing and spaced-apart oxide spacers to an ammonium fluoride gas comprises exposing the vertical, free-standing and spaced-apart oxide spacers to a mixture of ammonia and hydrogen fluoride. 
     
     
       3. The method of  claim 1 , wherein exposing the vertical, free-standing and spaced-apart oxide spacers to an ammonium fluoride gas comprises converting the convex portions of the vertical surfaces of the vertical, free-standing and spaced-apart oxide spacers to ammonium hexafluorosilicate ((NH 4 ) 2 SiF 6 ). 
     
     
       4. The method of  claim 3 , wherein a greater thickness of the convex portions than the concave portions of the vertical surface of the vertical, free-standing and spaced-apart oxide spacer is converted to ammonium hexafluorosilicate ((NH 4 ) 2 SiF 6 ) over a fixed period of time. 
     
     
       5. The method of  claim 3 , wherein removing at least a portion of the heat decomposable compound comprises applying heat, water or a combination thereof to the at least a portion of the heat decomposable compound. 
     
     
       6. The method of  claim 1 , wherein forming a patterned temporary material comprises forming the patterned temporary material comprising a photoresist material or amorphous carbon. 
     
     
       7. The method of  claim 1 , wherein depositing the oxide material onto the patterned temporary material comprises an atomic layer deposition or chemical vapor deposition. 
     
     
       8. The method of  claim 1 , wherein forming a patterned temporary material over an underlying material comprises forming the patterned temporary material over a material selected from the group consisting of a dielectric antireflective material, amorphous carbon, silicon nitride, polysilicon, crystalline silicon and metal. 
     
     
       9. The method of  claim 1 , wherein forming an oxide material comprises forming the oxide material selected from the group consisting of silicon oxide, ALD silicon oxide, tetraethylorthosilicate (TEOS) oxide, and silicon-rich silicon oxynitride (DARC). 
     
     
       10. A method of smoothing a vertical surface of an oxide material, the method comprising:
 exposing an oxide material to an ammonium fluoride gas to convert convex portions of a vertical surface of the oxide material within an opening to a heat decomposable compound; and 
 removing at least a portion of the heat decomposable compound to smooth the vertical surface of the oxide material within the opening. 
 
     
     
       11. The method of  claim 10 , further comprising, after removing at least a portion of the heat decomposable compound, forming an oxide material onto a vertical surface of the opening. 
     
     
       12. The method of  claim 11 , wherein forming an oxide material onto a vertical surface of the opening comprises an atomic layer deposition or chemical vapor deposition. 
     
     
       13. The method of  claim 10 , wherein the opening is a linear opening having a length. 
     
     
       14. The method of  claim 13 , wherein removing at least a portion of the heat decomposable compound to smooth the vertical surface of the oxide material within the opening comprises reducing line edge roughness (LER) of the vertical surface of the oxide material to provide about the same critical dimension (CD) along the length of the linear opening. 
     
     
       15. The method of  claim 14 , wherein the linear opening has an initial critical dimension that is variable along the length, and, after the exposing and removing, the linear opening has about the same critical dimension for the length of the linear opening. 
     
     
       16. The method of  claim 10 , wherein the heat decomposable compound has a thickness of about 0.1 nm to 5 nm. 
     
     
       17. A method of smoothing a vertical surface of an oxide material, the method comprising:
 exposing an oxide material to a mixture of ammonia and hydrogen fluoride to convert convex portions of a vertical surface of the oxide material within an opening in the oxide material to ammonium hexafluorosilicate ((NH 4 ) 2 SiF 6 ); and 
 removing at least a portion of the ammonium hexafluorosilicate ((NH 4 ) 2 SiF 6 ) to smooth the vertical surface of the oxide material within the opening. 
 
     
     
       18. The method of  claim 17 , wherein a greater thickness of the convex portions than the concave portions of the vertical surface of the oxide material is converted to ammonium hexafluorosilicate ((NH 4 ) 2 SiF 6 ) over a fixed period of time. 
     
     
       19. The method of  claim 17 , wherein removing at least a portion of the ammonium hexafluorosilicate ((NH 4 ) 2 SiF 6 ) comprises applying heat, water or a combination thereof to the at least a portion of the ammonium hexafluorosilicate ((NH 4 ) 2 SiF 6 ). 
     
     
       20. The method of  claim 17 , wherein the vertical surface of the oxide material within the opening has an initial edge profile comprising convex and concave areas and an initial convex-to-concave area line width roughness (LWR) amplitude, and the initial convex-to-concave area LWR amplitude is reduced after the exposing and removing.